Fix a broken chain crank

My 4 year old son was complaining of the chain kept coming off on his beloved toy pedal tractor (we live on a farm and he loves tractors more than anything!). I put the chain back on a couple of times and it kept slipping off..... I then noticed a crack in the crank that meant it bent ever so slightly and allowed the chain to come off.  The only way I could think of to fix it was with sugru!  I cleaned off the oil and use 2 packs of sugru to reinforce the crank, prevent the bend and stop the chain slipping off. This gave me one fixed tractor and one smiling son who thinks his dad is a genius!